Fluid pressure motor



Decl, 1959 L. J. LARsEN ErAL 2,915,046

FLUID PRESSURE MOTOR Filed April 1s. 195s 2 sheets-sheet 1 .HHH .n www mw Dec. 1, 1959 L. J. LARsEN ErAL FLUID PRESSURE MoToR 2 Sheets-Sheet 2 Filed April 18, 1956 FLUID PRESSURE Moron Lester I. Larsen, St. Joseph, and Charles A. L. Ruhl,

Kalamazoo, Mich., assignors to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application April 18, 1956, Serial No. 578,983

11 Claims. (Cl. 121--46) The present invention relates to fluid pressure motors, and more particularly to piston and cylinder arrangements having stop means which prevent the piston from being forced out of its cylinder by internal fluid pressure.

An object of the present invention is the provision of a new and improved fluid pressure motor of the piston and cylinder type and utilizing ball bearing stop means to prevent the piston from being forced out of its cylinder.

Another object of the present invention is the provision of a new and improved fluid pressure motor of the piston and cylinder type and utilizing ball bearing means to guide the piston relative to the side walls of the cylinder.

.Another object of the invention is the provision ofa new and improved Huid pressure motor of the above described type in which ball bearing means are utilized to both guide the piston and prevent fluid pressure from forcing the piston out of the cylinder.

Another object of the invention is the provision of a new and improved fluid pressure motor of the above described type in which the cylinder comprises a tubular portion whose side walls are deformed inwardly to form an abutment surface against which ball bearings carried by the piston abut toprevent the piston from being forced out of the cylinder.

-A further object of the invention is the provisionof a new and improved fluid'pressure motor of any of the above described types and utilizing a tapped hole in the side walls of the cylinder for feeding ball bearings to the inner portion of the piston when it is positioned in the cylinder chamber and which tapped hole is closed oi by v a screwed plug.

Further objects and advantages will be apparent to l those skilled in the art to which the invention relates from the following description of several preferred embodiments described with reference to the accompanying drawings forming a part of this specification and in which:

Figure l is a longitudinal cross sectional view of one embodiment of the invention;

Figure 2 is a fragmentary longitudinal sectional view of a second embodiment of the invention;

Figure 3 is a cross sectional view taken on lthe line 3 3 of Figure l;

Figure 4 is a cross sectional view taken'on the line 4 4 of Figure 2; and

Figures 5 and 6 are longitudinal cross sectional views of another embodiment of the invention.

The embodiment shown in Figure l generally comprises an open ended cylinder body A into which is inserted a piston member B, the opposite end portions of which contain suitable attachment means by which the piston and cylinder assembly may be connected between a stationary and a movable body.

The cylinder body A may be made in one or more pieces and as shown in Figure 1 is made in three sections, the first section being a generally tubular open end body having a longitudinally extending bore 12 adapted to slidingly receive andguide the piston B. The opposite gatented Dec. 1, 1959 2 end portion of the cylinder A is formed by"an end closure member 14 having a centrally located chamber 16 therein and a tapped passageway 18 communicating the'chamber 16 with the external surface of theend closure member 14 and adapted to receive a piping connection from a presameter of piston B, is sweated into counterbore 20 with its end abutting shoulder 26 and the opposite end of the tube 24 is sweated into a similar 'counterbore 28 in the adjacent end of tubular body 10. Counterbore 22 in end closure member 14 is of a diameter equal to that of the internal diameter of tube 24 so as to provide a cylindrical surface of constant diameter for a reason which will later he described.

The piston member B is adapted to extend into the cylinder A and may also be made in one piece, but as shown is conveniently made from a tubular Vmember 30 and an outer end piston closure member 32. The piston closure member 32 has an axially extending boss onone of its ends which is sweated into the outer end of the tubular member 30 of the piston B, and the opposite end of which piston closure member is provided with a hole 34 by which it may be bolted to a movable object.

The inner end of the piston B of the embodiment shown in Figure l is provided with an annular socket or groove 36 adapted to retain a plurality of ball bearings v38, such that the outer portions vof the ballscontact and roll *along -the inside surface of the tube 24 and counterboref22`previously indicated to be `of the same diameter. 'In the embodiment shown `in the drawing the cylinder end closure member 14 is provided with a tapped hole or opening 40 through which the ball bearings 38 may be fed to the annular groove or socket 3679i the piston, anda rthreadedplug 42 is screwedinto the opening 40` to prevent escape of the ball bearings. ,'.Ihe escape of fluid past the piston is preventedV by an O-ring 44 seatedin an annular groove 46 adjacent the outer end offopenend body 10, such that uid pressure entering passageway'ls forces thepiston B outwardly of the cylinder A. End closure member 14 is provided with a hole 48 Vwhereby it is adapted to be pivotally connected to aV ,stationary member. yFluid pressure entering through passageway 18 causes the piston B to be moved outwardly. Theball bearings 38 during such movement are retained ginlthe groove 36 and the piston is prevented fromv being forced out of the cylinder A upon the ball bearings 38 contacting the shoulder 50. y f l 'v v Figures 2 and 4 Figures 2 and 4 illustrate a second embodiment of th invention in which a plurality of individual ball bearing sockets 60 (in the present instance 3) are provided in the inner end of the piston B. The unit is otherwise quite similar to the preceding embodiment and the ball bearings 38 may be fed to the sockets in the same manner described for the preceding embodiment. The individual recesses or sockets 60 will preferably be spaced relative to the hole 34, by which the piston is attached to a movable object, by which the ball bearings are fed to the unit, such that the ball bearings 38 will not normally cross the'screw plug 42 when the unit is installed between a movable and astationary object. 'f

a cylinder'A made from a piece of tubular-material 52 having an annular end closuremember 54 through which I piston 56 extends andan opposite end closure member 58,

both of which are welded in place. 'I'he piston 56 is made from a piece of cylindrical rod and is provided with an lannular groove 60 adapted to receive the ball bearings 62. An annular fluid pressure seal 64 of U-shaped cross section is seated in a counterbore 66 in the outer end of the .cylinder to effect a seal with respect to the piston 56, and the seal 64 is held in place by an annular back-up washer 68 retained by a snap ring 70. A dirt seal or wiper ring 72 is positioned in the outer end of the counterbore 66 to keep dirt out of the fluid pressure seal 64.

Prior to assembly kof the unit shown in the drawings, the tube 52 is placed in a die and an inwardly extending projection or stop 74 is rolled into the metal. The unit is assembled by rst attaching the annular end closure member 54 to one end of the tube 52. The piston is then inserted through the tube and closure member until its upper end projects out of the closure member 54, whereupon the ball bearings 62 are fed to the groove 60. The piston 56 is then retracted into the tube 52 and the opposite end closure member 58 is then welded in place. The opposite end closure member 58 and the projecting end of the piston 56 are provided With attachment holes 48 and 34 respectively, and the closure member 58 is provided |with a tapped fluid pressure connection 76.

Operation of the above described device is believed to be obvious from the above description and attached drawings. Suilice it to say that the ball bearings 62 roll along the inside of tube 52 until they abut the crimped or stop portion 74 of the side walls of the tube.

While the preferred embodiments of the invention have been described as utilizing a cylinder chamber having a cylindrical surface adapted to confine the ball bearing ,means of the piston, it is not so limited. Where for example spaced individual -sockets are utilized to support the individual ball bearings, a longitudinally extending grove in the cylinder wall may be provided for each of the ball bearings such that rotation of the piston relative to the cylinder may be controlled, and indeed may be prevented, depending upon whether the grooves are straight or helically formed. It is further to be understood that the invention need not be limited to units wherein the ball bearing means are carried by the piston. Methods other than that described for feeding the ball bearings to the sockets may also be utilized, as for example by the use of a threaded connection between the cylinder end closure member and the remainder of the cylinder, which connection may be uncoupled to permit the balls to be placed in the sockets of the piston and the cylinder end closure member to be thereafter screwed into place.

Still other changes and modifications can be made to those embodiments shown in the drawings and while the preferred embodiments of the invention have been described in detail, I do not wish to be limited to the particular constructions shown which may be varied vwithin the `scope of the invention and it is the intention to cover hereby all adaptations, modications and arrangements thereof which come within the practice of those skilled in the art to which the invention relates.

We claim: l. A uid pressure motor comprising: an open ended cylinder body havingT a longitudinally extending chamber therein which opens outwardly of said cylinder body,

a cylindrical piston member projecting into said cylinder chamber, a plurality of ball bearings carried by the inner end of said piston and projecting radially outwardly of its cylindrical surface, said cylinder chamber having a cylindrical surface adjacent its open end to slidingly support said piston adjacent said open end of said cylinder body, and the inner portion of said chamber having longitudinally extending surfaces for receiving said ball bearings so as to support and guide the inner end of said piston.

2. A iluid pressure motorlcomprising an open ended cylinder body having a longitudinally extending chamber therein which opens outwardly of said cylinder body, a cylindrical piston member projecting into said cylinder chamber, and a plurality of ball bearings carried by the inner end of said piston and projecting radially outwardly of its cylindrical surface, said cylinder chamber having a cylindrical surface adjacent its open end to slidingly support said piston adjacent said open end of said cylinder body, and the inner portion of said chamber having longitudinally extending surfaces for receiving said ball bearings so as to support and guide the inner end of said piston, and a iluid pressure seal mounted in said cylindrical surface of said chamber adjacent its open end.

3. A fluid pressure motor comprising: an open ended cylinder body having a longitudinally extending chamber therein which opens outwardly of said cylinder body, a cylindrical piston member projecting into said cylinder chamber, a plurality of ball bearings carried by the inner end of said piston and projecting radially outwardly of its cylindrical surface, said cylinder chamber having a cylindrical surface adjacent its open end to slidingly support said piston adjacent said open end of said cylinder body, and the inner portion of said chamber having longitudinally extending surfaces for receiving said ball bearings so as to support and guide the inner end of said piston, said receiving, supporting and guiding surfaces terminating in shoulders at their ends closest to the open end of said chamber and against which said ball bearings abut to prevent separation of said piston from said cylinder body.

4. A uid pressure motor comprising an open ended cylinder having a longitudinally extending chamber of a first predetermined diameter adjacent its inner end and a smaller predetermined diameter adjacent its open end, a cylindrical piston member projecting into said open ended cylinder, and a plurality of ball bearings carried by the inwardly positioned portion of said piston and projecting radially outwardly of the cylindrical surface of said Ipiston to engage the walls of the rst predetermined diameter section of said chamber.

5. A uid pressure motor comprising an open ended cylinder having a longitudinally extending chamber of a first predetermined diameter adjacent its inner cnd and a smaller predetermined diameter adjacent its open end, a cylindrical piston member projecting into said open ended cylinder and having a circumferentially extending groove on its inwardly positioned portion, and a plurality of ball bearings seated in said circumferentially extending groove and bearing against the inside surface of said inner portion of said chamber.

6. A fluid pressure motor comprising an open ended cylinder having a longitudinally extending chamber of a first predetermined diameter adjacent its inner end and a smaller predetermined diameter adjacent its open end, a cylindrical piston member projecting into said open ended cylinder and having a plurality of individual sockets therein, and a plurality of ball bearings each of which are seated in one of said individual sockets and bear against the inside surface of said inner portion of said chamber.

7. A fluid pressure motor comprising an open ended cylinder having a longitudinally extending chamber of a first predetermined diameter adjacent its inner end and a smaller predetermined diameter adjacent its open end, a cylindrical piston member projecting into said open ended cylinder and having a circumferentially extending groove on its inwardly positioned portion, a plurality of ball bearings seated in said circumferentially extending groove and bearing against the inside surface of said inner portion of said chamber, said cylinder having a tapped hole extending between said rst predetermined diameter portion of said chamber and the external surface of said cylinder, and a tapped plug closing off said tapped hole of said cylinder.

8'. A iluid pressure motor comprising an open ended cylinder having a longitudinally extending chamber of a rst predetermined diameter adjacent its inner end and a smaller predetermined diameter adjacent its open end, a c

cylindrical piston member projecting into said open ended cylinder and having a plurality of individual sockets therein, a plurality of ball bearings each of which are seated in one of said individual sockets and bears against the inside surface of said inner portion of said chamber, said cylinder having a tapped hole extending between said first predetermined diameter portion of said chamber and the external surface of said cylinder, and a tapped plug closing off said tapped hole of said cylinder.

9. A fluid pressure motor comprising a tubular member, an annular member attached to one end of said tubular member, a cylindrical piston member of uniform diameter projecting into saidtubular member through said annular member, sealing meansr positioned between said annular member and said piston member, said piston member having recess means in the surface thereof located adjacent the inner end of said piston member, at least three ball bearings in said recess means, said recess means being constructed and arranged to circumferentially space the ball bearings around said piston member with their outer surface substantially in engagement with the inside surface of said tubular member, and an end closure member attached to the other end of said tubular member, the side walls of said tubular member being radially inwardly deformed to provide an abutment surface against which said ball bearings abut to prevent the withdrawal of said piston member from said tubular member.

10. A uid pressure motor comprising a tubular member, an annular member attached to one end of said tubular member, a cylindrical piston member of uniform diameter projecting into said tubular member through said annular member, sealing means positioned between said annular member and said piston member, said piston member having a circumferentially extending recess in the portion of its surface positioned inside said tubular member, a plurality of ball bearings in said recess with their outer surface substantially in engagement with the inside surface of said tubular member, and an end closure member attached tothe other end of said tubular member, and at least a portion ofthe side walls of said tubular member positioned between said ball bearings and said annular member being deformed inwardly to provide an abutment surface against which said ball bearings abut to prevent the withdrawal of said piston member from said tubular member.

l1. A lluid pressure motor substantially as set forth in claim 9 characterized further in that said annular member and said end closure member are welded to said tubular member to form an inexpensive throw away type of unit.

References Cited in the tile of this patent UNITED STATES PATENTS 2,201,739 Nicholson May 2l, 1940 2,682,256 Bowman June 29, 1954 2,724,368 Miller Nov. 22, 1955 

